#include<iostream>
using namespace std;
int C(int k, int n) {
	if (k == 0 || k == n) return 1;
	if (k == 1) return n;
	return C(k - 1, n - 1) + C(k, n - 1);
}
int main(){
	int n, k;
	cout << "Nhap k: ";
	cin >> k;
	cout << "Nhap n: ";
	cin >> n;
	cout << "To hop bang: " << C(k, n);
	system("pause");
	return 0;
}